Fluorescent pteridine-based nucleoside analogs that can be site-specifically incorporated into DNA oligonucleotides through a phosphodiester linkage have been developed and patented. The fluorescence properties of a series of these compounds have been characterized and potential applications are being investigated. These new fluorophores are promising probes for the study of protein/DNA interactions, because they are not attached to DNA externally and they do not appear to disrupt the tertiary structure of DNA. The utility of these fluorophores as hybridization probes has been investigated and patented. Collaborative studies to investigate other applications for these new probes are also ongoing and the Imaging Probe Development Center (IPDC), which is part of the NIH Roadmap Initiative, has selected these compounds for development.